Since the development of light-cured resins suitable for use on tooth surfaces, a number of different devices and methods have been developed for curing the resins.
Originally, halogen lamps were used, directing the energy through a narrow steel tube or along a fused glass bundle wave guide to the treatment site. Since the output is broadband, the lamp, tube or waveguide must contain a blue filter to remove most of the unwanted energy outside the desired frequency band. This arrangement is large, inefficient, complex and requires connection to an AC electrical outlet. The filters tend to have short useful lives and pass some other light in addition to the desired blue light, which will tend to undesirably heat the treatment area and the lamp reflectors degrade with time.
Powerful lasers, such as argon ion lasers which emit at a number of discrete spectral lines have been used. These lasers are expensive, have a limited lifetime, are inefficient converters of electrical energy into blue light and generate large amounts of heat. The use of diode pumped crystals which double the input frequency into the blue spectrum have been proposed, as have plasma arc tubes. These units are large, complex and expensive, requiring electrical connection to a high power source. The handpiece used to direct the energy to the treatment site tends to be large and to be restrictive and unwieldy due to the wiring to an external electrical supply.
Attempts have been made to use the recently developed blue light emitting diodes (LED), which require no filter. Typically, a plurality of LED's are arrayed at the large end of a tapered glass member or are positioned so that each LED feeds one fiber of a fiber bundle. Unfortunately, these arrangements have considerable coupling and taper/fiber losses.
Thus, there is a continuing need for improved light sources for use in curing resins coated on teeth which will produce a narrow band of wavelengths, usually in the blue light region, that are simple, reliable, efficient and inexpensive, that are small, light weight and self contained with no need for external wiring.